The major objective of this program is to identify aspects of impaired information processing which may represent a central feature of childhood and early adolescent onset schizophrenia. Specifically, we will compare schizophrenic children and adolescents, ages 9-15, with age and I.Q. matched normal children on eventrelated brain potential (ERP) measures known to be associated with automatic nonattentional processing, selective attention, and controlled, effortful processing in stimulus categorization and discrimination. Our basic aim is to examine the spatial and temporal pattern of these ERP components to help us understand to a greater extent than is possible in purely behavioral studies, the nature and timing of information processing failures in schizophrenia. ERPs will be elicited during performance of tasks of demonstrated sensitivity to schizophrenia, and for which the relationship of particular ERP components to particular cognitive operations has been established. The Span of Apprehension requires identification,during brief visual exposure, of a target letter surrounded by distractor letters. The second paradigm involves selective attention to one of two auditory input channels. The subject must respond to an infrequently occurring target tone in the attended channel(ear) while ignoring its occurrence in the unattended channel (ear). ERPs will be analyzed using subtraction methods, peak measures and Principal Components analysis to identify components, and extensive topographic mapping will be done to better characterize the obtained components, and to identify regional differences in these measures. An age-matched group of children with Attentional Deficit Disorder (ADD) will serve as an important contrast group. These children suffer attentional disorders but are not psychotic. The study of ADD children should aid in the determination of the specificity of our finding with respect to schizophrenia.